The processing of pulp fibers requires several steps before the fibers can be used to manufacture paper. Some of these processes include pressing, washing and liquor extraction. These steps are performed by presses and washers that contain filtering surfaces with openings large enough for some fibers to pass through. The liquor, while flowing through the filtering surface therefore, carries with it a certain amount of fibers.
It is highly desirable to capture the fibers contained in the filtrate as they would otherwise represent loss of usable product and a source of disposal problems. In order to capture the fibers a filtering surface with openings small enough so that only the liquid can go through is required. This permits the collection of fibers. Such a machine is referred to by the present assignee as a Fibresaver Screen. There is a market demand for a screen with openings of 0.004" in diameter, or even smaller. The filtrate of the other machines described above would be fed into this machine in order to recover as many fibers as possible. Typically such a screen may be formed into the shape of a basket or hollow cylinder. Due to the manufacturing process and the economics of manufacturing a screen basket with very small openings the basket thickness cannot exceed a certain value. Usually the smaller the opening, the thinner the basket. For example, a basket with 0.1 millimeter (0.004" ) holes would have a thickness of no more than 1 millimeter (0.04" ). In a production machine of any size a screen basket of this thickness requires a supporting structure in order to handle the loads acting on it without failing.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.